The present invention generally relates to apparatus and methods for the support of surface structures. More specifically, the present invention provides improved pre-cast footing components configured for integration with the wall element of traditional foundations to create minimally intrusive foundation systems.
The construction of surface structures invariably involves the preliminary task of building a foundation to support the structure. Most foundations prepared in current practice are comprised of a load bearing base known as a footing which is site poured with a cementious material into an excavation substantially below grade. The excavation provides for the footing to be founded on competent bearing soils beneath regional frost lines. Once cured, forming boards and a grid of internal reinforcing are constructed on top of the footing, allowing for the subsequent pouring of a cementious material to form a wall rising out of the excavation to a desired height above grade.
The impetus to install foundations that have minimal environmental impact has become prevalent in many areas. The effects of site manipulation on undisturbed soil are permanent and not restricted to the individual sites on which they occur. xe2x80x9cImprovingxe2x80x9d a site with the use of large machinery, extensive excavation and fill techniques, and the altering of drainage patterns and water tables damages the biological make up, structural integrity, and pre-existing drainage characteristics of the specific and surrounding soils. This in turn can have damaging effects xe2x80x9cdownstream,xe2x80x9d where the accumulation of unwanted eroded material in streambeds can alter plant and animal habitat. Man-made structures designed to replace the storage and filtering function of previously undisturbed soils by capturing unwanted drain waters and releasing them slowly back to the stream systems, can starve the watershed of its historic flow patterns, again causing damage to the environment and water quality.
Innovation in foundation design and construction must consider not only low environmental impact, but economical construction that is adaptable to the widest possible range of architectural typologies. For low impact construction systems to have significant effects toward improving the environment and ensuring the sustainability of our population and its building techniques, their use must be widespread and quickly adoptable into the mainstream of current development practice.
U.S. Pat. No. 5,039,256 discloses systems that rectify many of the environmental problems discussed above. The disclosure of U.S. Pat. No. 5,039,256 is hereby incorporated by reference. The present invention expands on the objectives disclosed in U.S. Pat. No. 5,039,256 and provides a low impact footing system that can be integrated directly with traditional foundation walls, thereby eliminating the traditional and separate subsurface footing. The resulting foundation uses less material than traditional foundation assemblies, and is more easily implemented on site by construction personnel.
An object of this invention is to provide an improved foundation system that incorporates pre-cast load bearing components.
An object of this invention is to provide an improved foundation system implementing traditional leveling techniques including step down configurations of the foundation sill.
An object of this invention is to provide an improved foundation system that avoids the need for special wood framing techniques in the construction of the surface structure to correct for a sloping foundation sill.
An object of this invention is to provide a new method for constructing structural foundations which is applicable to a wide variety of site and soil conditions and architectural typologies.
An object of this invention is to provide a new method for constructing structural foundations which utilizes pre-cast components light enough for the installer to carry and position on site.
An object of this invention is to provide a new method for constructing structural foundations which utilizes pre-cast components that have seating tabs designed for the specific placement of standard wall forms.
Another object of this invention is to provide a foundation which is applicable for uniformly or non-uniformly distributed loading conditions, and concentrated or point loading conditions.
Another object of this invention is to provide a foundation which is applicable for retaining wall load conditions.
Another object of this invention is to provide a foundation which is applicable for decorative cementious wall applications, supporting their own weight.
A further object of this invention is to provide a method for constructing a foundation system which will require substantially less or no site excavation for above grade buildings.
A further object of this invention is to provide a method of constructing a foundation system without significantly damaging or altering the moisture content, drainage characteristics, biological make-up, or structural integrity of the soil which it engages.
It is also an object of this invention to provide a foundation system which has parts that are easily maintained and/or replaced.
It is also an object of this invention to provide a foundation system which can be applied repeatedly as a standardized construction component with a specific load bearing capacity, and structural function.
The above and other objects of the present invention are realized in a pre-cast component comprised of four basic parts which in combination with a traditional foundation wall form a hybridized foundation system integrating driven pile, pre-cast component, and poured in place cementious wall technologies. Specifically, the pre-cast or (prefabricated) components are used in combination with driven piles and the above grade wall component of a traditional foundation. The current invention is constructed at grade without any (or in some cases only a very minimal) excavation. The series of pre-cast components contain openings with sleeves for receiving obliquely driven piles, and a central passageway within which a traditional foundation wall component is engaged. The piles, which reach to the appropriate soil bearing strata described above, are driven through the sleeves in the pre-cast components at angles and to depths determined by specific loading criteria. The pre-cast component is comprised of two halves separated by a predetermined distance relative to the width of the traditional foundation wall it is to engage. These two halves are held at this predetermined separation by the driving sleeves, which are in turn held in their respective positions by the pre-cast material of the two halves. The sleeves are further restricted in this position by a reinforcing element that engages both them and the pre-cast halves at once. The resulting assembly provides a structure for the positioning of the piles, and, in concert with them, becomes a load bearing element, that when used in series, can be integrated with a traditional foundation wall. When properly aligned and spaced according to the loading criteria of the structure to be supported, the series of integrative pre-cast footings, (xe2x80x9cIPFxe2x80x9d) provides a framework for the placement of the lower horizontal members of the foundation wall reinforcing grid, for the erection of foundation formwork, and for the subsequent site pouring of a cementious material for the wall.
In concert, the entire assembly provides a low impact foundation, installed without, or with only minimal, excavation. The base of the intended surface structure is attached to the top (sill) of the resulting foundation using any appropriate conventional connection method. Once attached, the surface structure will rest directly on the formed foundation, transferring its loads through the wall and its engaged pile based, pre-cast footing components into the bearing soils below. The entire assembly is also applicable to both retaining and decorative foundation wall applications. The grouping of obliquely driven piles in specific, geometric configurations and their relationship to the pre-cast footings integrated into a continuous foundation wall according to a specific alignment and spacing relates directly to the loading characteristics and capacity of the system. The present invention, through its engineered design, ensures that these relationships remain fixed, allowing the entire assembly to resist gravitational, lateral, and uplifting forces in accordance with the demands at each installation.
The foregoing features of the present invention are more fully described from the following detailed discussion of a specific illustrative embodiment thereof, presented herein below in conjunction with the accompanying drawings.